1. Field of the Invention
The present invention relates to an infrared light detection array and a method of Producing the same, and more particularly, to an infrared light detection array having infrared light detectors correctable supporting angles of heat insulation structure portions and a method of Producing the same.
2. Description of the Related Art
FIG. 22 is a cross sectional view of an infrared light detector indicated in its entirety by 700 and described in JP, 10-253447, A. The infrared light detector 700 includes a semiconductor substrate 701. A support leg 702 is disposed on the semiconductor substrate 701. Further, one end of a displaceable portion 705 is fixed to the supporting leg 702, and the displaceable portion 705 is supported in midair. The displaceable portion 705 has a laminated structure of an infrared absorbing film 703 and a reflection film 704.
In the infrared light detector 700, as infrared light impinges upon the displaceable portion 705, the infrared absorbing film 703 absorbs the infrared light and converts the light into heat. Since thermal expansion coefficients of the infrared absorbing film 703 and the reflection film 704 forming the displaceable portion 705 are different from each other, if the displaceable portion 705 is heated, the displaceable portion 705 warps in accordance with the bi-material principle.
As the displaceable portion 705 warps, the reflection angle of reading light irradiating upon the reflection film 704 changes. Hence, as this change is detected as a change in reflection intensity at a predetermined detection position, the incident infrared light is detected.
Meanwhile, JP, 2000-326299, A as well describes an infrared light detector having an approximately same structure utilizing the bi-material principle.
In an infrared light detection array with such infrared light detectors 700 arranged each as one pixel, even if uniform infrared light is irradiated upon all pixels, the reflection intensities of reading light do not become uniform since the angles of the reflection films 704 with respect to the semiconductor substrate 701 are not uniform among the pixels. Hence, there is a problem that the intensities of reflected reading light are not uniform and an image deterioration called a fixed pattern noise is created. Further, there is another problem that even when the quantity of infrared light incident upon the infrared light detectors 700 is changed, the angles of the reflection films 704 do not similarly change among all pixels.
Although a method according to dispose interference of reading light for each pixel so as to reduce variations among the pixels has been proposed to solve these problems, it is difficult to ensure that an interference condition is constant among all pixels, and therefore, it is impossible to remove a fixed pattern noise.
Meanwhile, other method has been proposed to have a CCD camera or the like capture reflection light of reading light and to electrically correct an imaging signal. However, although realizing removal of a fixed pattern noise, this method demands a camera, a signal correction circuit, etc., and therefore, there is a problem that a cost for a detection system including infrared light detectors is very high.